give it time. most things will blow over. Wait. Then when you feel its the right time approach them with an explanation or an apology if needed. Dont Accuse them or blame them it won't solve anything.
Nothing happens you are her bff. Well it depends if you text over and over again she probably doesn't have her phone. It also depends on if you've had any recent fights. If you haven't you have nothing to worry about.
if it is a girl ask her y and fix it if it is a boy ignour and he will come around
Unfortunately, your friend is not as good a friend as you think because if they can text your best friend then there is no reason they can't text you. Even though it hurts you ignore this friend and a wise decision would be to drop this friend and find a new one and that goes for your best friend as well as it sounds like something is going on where they want to leave you out of their text messaging.
If you still like your best friend then try to get her back or let her go with your sister if that's what your friend wants. Or mabey your friend could be friends with your sister and best friends with you.
Facetime or text them
text them if broken up text to say sorry
if your a girl he is imbarresed or thinks the same, and if ur a guys...your scaring him
boyfriend or best friend
BFF means Best Friend Forever. It is just a text shortcut for "my best friend" or "my good friend."
he's not worth trying to help when he ignores and lies to you
When you talk to her and she ignores you.
Text her back.